System for improving performance of thermal power plant

Abstract

A thermal power plant performance improvement system is disclosed that can improve efficiency and reduce greenhouse gases and air pollutants by partially modifying an existing thermal power plant. The thermal power plant performance improvement system is characterized by including a boiler of the thermal power plant, a flue connected to the boiler and guiding exhaust gas generated from the boiler, and a heat generation block connected to the flue and generating electricity using a portion of the heat from the exhaust gas.

Description

Technology Field

[0001] The present invention relates to a technology for improving the performance of a thermal power plant, and more specifically, to a thermal power plant performance improvement system capable of changing the capacity of a fan, wherein a fan is installed to improve efficiency and reduce greenhouse gases and air pollutants by partially modifying an existing thermal power plant. Background Technology

[0002] Recently, plans for new installations of coal-fired power plants have been decreasing due to the expansion of renewable energy and gas turbines, and the decommissioning of decades-old coal-fired power plants is expected to expand due to stricter environmental regulations. According to the 9th Power Supply and Demand Plan, a total of 30 coal-fired power plants are expected to be decommissioned or replaced through fuel conversion.

[0003] Therefore, retrofitting existing thermal power plants to maximize their lifespan and improve efficiency in preparation for greenhouse gas reduction can be seen as a realistic alternative for utilizing thermal power plants without waste.

[0004] Generally, large boilers are configured with a system in which a superheater and a reheater (RH) are installed in the high-temperature section, a primary superheater and an economizer are installed in the medium-temperature section, and a denitrification system (SCR: Selective Catalytic Reduction) and a gas air heater (GAH) are installed in the low-temperature section. The economizer is also composed of Economizer 1 and Economizer 2.

[0005] Meanwhile, the combined heat and power generation facility, which is a medium / small boiler, does not have a reheater (RH) and is composed of a superheater consisting of about two stages, and is configured as a system in which an economizer or an air preheater, or a combination of an economizer and an air preheater, is installed in the medium / low temperature section.

[0006] The fuel is combusted in the furnace, and after heating the water in the heater, it passes through the economizer, SCR, GAH, EP (Electrostatic Precipitator), ID (induced draft) FAN, and FGD (Flue Gas Desulfurization) before exiting into the stack.

[0007] Meanwhile, while the application of heat recovery systems in power generation facilities was previously limited to the purpose of reducing fuel costs, recently, the necessity has been increasing not only for fuel cost reduction but also for compliance with environmental regulations, such as greenhouse gas reduction and pollutant emission reduction. Prior art literature

[0008] 1. Korean Registered Patent No. KR10-1822311 (Registration Date: January 19, 2018) The problem to be solved

[0009] The present invention is proposed to resolve the problems according to the background technology described above, and aims to provide a thermal power plant performance improvement system capable of changing the capacity of a ventilator to improve efficiency and reduce greenhouse gases and air pollutants by partially modifying an existing thermal power plant.

[0010] In addition, another objective of the present invention is to provide a thermal power plant performance improvement system and method that can economically save social costs by increasing the operating time of the power generation system.

[0011] In addition, another objective of the present invention is to provide a thermal power plant performance improvement system and method that can utilize temperatures up to 90 to 95°C and obtain additional power generation output. means of solving the problem

[0012] To achieve the objectives set forth above, the present invention provides a thermal power plant performance improvement system capable of improving efficiency and reducing greenhouse gases and air pollutants by partially modifying an existing thermal power plant.

[0013] The above thermal power plant performance improvement system is,

[0014] A boiler in a thermal power plant;

[0015] A flue connected to the above boiler and guiding exhaust gas generated from the above boiler; and

[0016] It is characterized by including an array power generation block connected to the above year that generates power using a portion of the excess heat from the exhaust gas.

[0017] In addition, the above-mentioned array power generation block is characterized by being placed in the low-temperature section of the boiler and connected to the downstream end of a denitrification unit that removes harmful substances from the exhaust gas.

[0018] In addition, the above-described array power generation block is characterized by comprising: a damper for introducing the exhaust gas; a heater for heating a working fluid using the introduced exhaust gas; a turbine for rotating using the heated working fluid; a generator connected to the turbine that rotates by the turbine to generate power; a compressor for compressing the working fluid that has passed through the turbine to produce a compressed working fluid; a heat exchanger in which heat exchange takes place between the compressed working fluid discharged from the compressor and the working fluid that has passed through the turbine; and a cooler for cooling the working fluid that has undergone heat exchange by the heat exchanger.

[0019] In addition, the above working fluid is characterized as being carbon dioxide or a refrigerant.

[0020] In addition, the array power generation block is characterized by including an array recovery unit connected to the output end of the heater, which releases the exhaust gas into the atmosphere or returns it to the flue side.

[0021] In addition, the array recovery unit is characterized by being connected to the front or rear end of an electrostatic precipitator installed in the above-mentioned flue to return the exhaust gas to the front or rear end of the electrostatic precipitator.

[0022] In addition, the array recovery unit is characterized by returning the exhaust gas only to the front end of the electrostatic precipitator when the temperature of the exhaust gas that has passed through the heater is lower than a preset reference value.

[0023] In addition, the above-mentioned array recovery unit is installed within the above-mentioned flue and is connected to the front or rear end of a flue gas desulfurization unit installed at the front end of the flue, thereby returning the exhaust gas to the front or rear end of the flue gas desulfurization unit.

[0024] In addition, the pressure within the above-mentioned year is characterized by being maintained at a constant level using an additional blower.

[0025] On the other hand, another embodiment of the present invention provides a method for improving the performance of a thermal power plant, characterized by comprising: (a) a step of inducing exhaust gas generated in a boiler through a flue communicating with the boiler of the thermal power plant; and (b) a step of connecting an array power generation block to the flue to generate power using a portion of the excess heat from the exhaust gas. Effects of the invention

[0026] According to the present invention, a heat recovery generator is connected for the repowering of a thermal power plant that uses coal or heavy oil as fuel, thereby improving the efficiency of the entire thermal power generation system and reducing greenhouse gas emissions.

[0027] In addition, another advantage of the present invention is that if the exhaust gas of a thermal power plant is utilized only with a Gas Air Heater (GAH) as in the conventional manner, only heat up to about 175°C can be utilized, but by utilizing a heat recovery generator, the temperature up to 90-95°C can be utilized and additional power output can be obtained, thereby increasing power generation efficiency and enabling conversion to an eco-friendly power plant.

[0028] In addition, another advantage of the present invention is that the gas flow rate required in the heater of the array generator is a bypass flow rate that is lower than the boiler combustion gas flow rate of the thermal power plant, so the impact on the overall boiler performance of the thermal power plant is minimal, and some combustion gas can be utilized by connecting it to the SCR (Selective Catalytic Reduction) outlet gas duct at the economizer outlet.

[0029] In addition, another advantage of the present invention is that when connected to the GAH outlet, the system requirements can be met by installing a separate ID (Induced Draft) fan to achieve pressure balance. Brief explanation of the drawing

[0030] FIG. 1 is a block diagram of a thermal power plant performance improvement system according to an embodiment of the present invention. Figure 2 is a detailed configuration diagram of the power generation block shown in Figure 1. Figure 3 is a conceptual diagram showing the exhaust gas flow of a thermal power plant in the thermal power plant performance improvement system illustrated in Figure 1. FIG. 4 is a gas temperature curve according to the position of the heat transfer surface of a 500MW class power generation boiler according to one embodiment of the present invention. FIG. 5 is a gas temperature curve according to the position of the heat transfer surface of a 100MW class power generation boiler according to an embodiment of the present invention. Specific details for implementing the invention

[0031] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. The sizes and relative sizes of components shown in the drawings may be exaggerated for clarity of description.

[0032] Throughout the specification, the same reference numerals refer to the same components, and “and / or” includes each of the mentioned items and all combinations of one or more.

[0033] The terms used herein are for describing embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, “comprising” and / or “consisting” does not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0034] Although various components such as the first and second are used to describe them, it goes without saying that these components are not limited to these terms. These terms are used merely to distinguish them from a single component. Therefore, it goes without saying that the first component mentioned below may be the second component within the technical scope of the present invention.

[0035] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0036] A thermal power plant performance improvement system and method according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0037] FIG. 1 is a block diagram of a thermal power plant performance improvement system (100) according to an embodiment of the present invention. Referring to FIG. 1, the thermal power plant performance improvement system (100) may be configured to include a boiler (102), a flue (103), a heat generation block (140), a chimney (170), etc. The boiler (102) may be configured to include a high-temperature section (110) with a furnace, a medium-temperature section (120) located in the flue (103), a low-temperature section (130), etc.

[0038] A platen superheater (111), a final superheater (112), and a final reheater (113) are arranged in the high-temperature section (110). The platen superheater (111) is a superheater installed in a boiler at a high temperature of the combustion gas and has a heat transfer surface in the shape of a plate.

[0039] In the medium temperature section (120), a cold reheater (121), a primary superheater (122), and an economizer (123) are arranged. The economizer (123) functions to increase the efficiency of the boiler and save fuel by recovering the heat lost by raising the feedwater temperature through the waste heat from the boiler combustion exhaust gas. The economizer (123) consists of a primary economizer (123-1) and a secondary economizer (123-2).

[0040] The flow of the cold reheater (121) is in the order of FSH → HP (High Pressure) turbine → Cold RH (Reheater) (121) → Final RH → IP (Intermediate Pressure) turbine. The cold reheater is where low-temperature, low-pressure steam that has worked in the HP turbine enters.

[0041] In the low-temperature section (130), a Selective Catalytic Reduction (SCR) unit (131) and a Gas Air Heater (GAH) (132) may be installed. The Selective Catalytic Reduction (SCR) unit refers to a selective catalytic reduction device. It performs the function of removing nitrogen oxides by spraying a catalyst into the exhaust gas coming out of the boiler's combustion chamber to decompose harmful substances, such as nitrogen oxides (NOx), into nitrogen and water.

[0042] The air preheater (132) performs the function of preheating combustion air using residual heat from the combustion gas. The combustion gas is flue gas, which refers to the gas generated while burning fossil fuels such as coal and petroleum.

[0043] The flue (103) is a duct structure, and an electrostatic precipitator (EP) (136), a fan (150), a flue gas desulfurization (FGD) (160), a stack (170), etc., may be placed in the flue (103). The electrostatic precipitator (136) performs the function of collecting fine dust. To this end, the electrostatic precipitator (136) is composed of a discharge wire (not shown) that charges the dust and collecting plates (not shown) that collect the charged dust.

[0044] A heat generation block (140) is connected to the medium temperature section (130) of the boiler (102). The heat generation block (140) performs the function of generating power by recovering (i.e., heat recovery) a portion of the excess heat generated inside the boiler (102). For heat recovery, the heat generation block (140) may utilize a steam turbine (Rankine cycle), supercritical CO2 power generation, ORC (Organic Rankine Cycle) power generation, Kalina power generation, Brayton cycle power generation, etc., and may be modified for optimization.

[0045] Depending on the temperature of the exhaust gas, a dry electrostatic precipitator may be placed at the front end of the flue gas desulfurization unit (160), and a wet electrostatic precipitator or a nonwoven fabric filter may be applied at the rear end.

[0046] In the case of an electrostatic precipitator, when a high voltage is applied to a charged element, an electric field is formed between the charged element and the collecting plate. The gas surrounding the charged element is ionized and collides with dust, causing the dust to become charged. The charged dust adheres to the collecting plate due to the Coulomb force, thereby purifying the air.

[0047] The fan (150) is an ID (induced draft) FAN and performs the function of introducing exhaust gas into the flue gas desulfurization unit (160).

[0048] The flue gas desulfurization unit (160) performs the function of removing sulfur oxides from exhaust gas. Sulfur oxide reduction technology is broadly classified into wet and dry desulfurization, and wet desulfurization equipment (Wet FGD) is used worldwide.

[0049] The chimney (170) is a structure that performs the function of discharging exhaust gas from which sulfur oxides have been removed. The tank (101) is a tank that acts as a type of separator. Water (steam) goes from tank (101) → PSH (112)→ Move from Platen SH(111) → FSH(113).

[0050] FIG. 2 is a detailed configuration diagram of the array power generation block (140) illustrated in FIG. 1. Referring to FIG. 2, the array power generation block (140) has a Brayton cycle that undergoes compression, heating, expansion, and cooling processes. Of course, depending on the working fluid and the cycle, other cycles such as the Rankine cycle are also possible.

[0051] The array power generation block (140) may be configured to include a damper (210) for introducing exhaust gas, a heater (PHX) (220) for heating a working fluid using the introduced exhaust gas, a turbine (T) (260) for rotating using the heated working fluid, a generator (270) connected to the turbine (260) and rotating by the turbine (260) to generate power, a compressor (C) (250) for compressing the working fluid that has passed through the turbine (260) to produce a compressed working fluid, a heat exchanger (R) (230) in which heat exchange occurs between the compressed working fluid discharged from the compressor (250) and the working fluid that has passed through the turbine (260), and a cooler (CH) (240) for cooling the working fluid that has undergone heat exchange by the heat exchanger (230).

[0052] The damper (210) performs the function of controlling or blocking the amount of flowing exhaust gas. To this end, it has a wing structure.

[0053] The exhaust gas discharged from the boiler (102) travels through the damper (210) to the heater (220) to heat the working fluid, and is discharged into the atmosphere or returned to the thermal power plant. The heat from the exhaust gas supplied to the heater (220) provides heat to the power generation cycle of the heat recovery power generation block (140). The working fluid may be carbon dioxide, a refrigerant, etc. Possible refrigerants may be HFC-245fa, R245ca, HCFC-123, etc.

[0054] Exhaust gas at 300°C to 400°C heats the working fluid and can be discharged into the atmosphere or recirculated into the power generation system to meet exhaust gas standards (dust, sulfur oxides, nitrogen oxides) for environmental protection.

[0055] If only a small amount of exhaust gas is extracted for array generation and used in the array generation block (140), and meets environmental regulations, it may be released into the atmosphere without passing through environmental facilities (combined with a large amount of environmentally treated exhaust gas).

[0056] FIG. 3 is a conceptual diagram showing the exhaust gas flow of a thermal power plant in the thermal power plant performance improvement system (100) illustrated in FIG. 1. Referring to FIG. 3, a heat recovery unit (310) is configured. The heat recovery unit (310) is connected to a heater (220), and after heating the working fluid in the heater (220) with the heat of the exhaust gas introduced through the damper (210), the heat recovery unit (310) vents the exhaust gas to the atmosphere.

[0057] Of course, the heat recovery unit (310) can send exhaust gas to the front or rear end of the electrostatic precipitator (136) (i.e., the front end of the blower (150)) to meet environmental standards or pressure balances required for exhaust gas, or depending on the flow rate of additional exhaust gas. If the temperature of the exhaust gas returned after being sent to the heat generation block (140) is low and does not provide much help to the air preheater (132), it is sent to the front end of the electrostatic precipitator (136). Of course, for this purpose, the heat recovery unit (310) may be equipped with a temperature sensor. The temperature range may be 300 to 400°C.

[0058] Alternatively, the exhaust gas can be returned to the front end (i.e., the rear end of the ventilator (150)) or the rear end of the flue gas desulfurization unit (160).

[0059] Additionally, the array recovery unit (310) may be configured to include a part of the array power generation block (140), or the array recovery unit (310) may be configured to include a part of the array power generation block (140). Accordingly, the array recovery unit (310) may be configured to include a microprocessor, a microcomputer, a memory, a duct (not shown), an air conditioning damper (not shown), etc. To elaborate, by controlling the direction and opening / closing of the air conditioning damper (not shown) according to the control of the microprocessor, the inflow or blocking of exhaust gas into the duct connected to the front or rear end of the electrostatic precipitator (136) (i.e., the front end of the fan (150)) or the front or rear end of the flue gas desulfurization unit (160) (i.e., the rear end of the fan (150)) is performed.

[0060] In addition, if the flow rate of exhaust gas that must be returned to the thermal power plant is low, or if the original fuel is clean and there is no need to remove dust or sulfur oxides, it may be released directly into the atmosphere.

[0061] At this time, the pressure of the entire system (i.e., within the flue (103)) must be balanced. To balance the pressure, additional fans (i.e., ID FANs) may be installed, or the capacity of the FANs may be changed. If the exhaust gas does not need to be returned to the thermal power plant, the exhaust gas may be discharged directly into the atmosphere.

[0062] In one embodiment of the present invention, equipment (210, 310) that was not present in the existing power plant is added. When exhaust gas passes through these facilities, pressure loss occurs. An ID FAN is required to compensate for this pressure loss. The value of this pressure loss must be at a level similar to the pressure loss predicted by the initial system.

[0063] Depending on the location where exhaust gas is discharged or joined, the fan may be installed at the point where the heat recovery unit is released to the atmosphere or joined to compensate for additional pressure loss. If an FD FAN is used, it may be installed at the inlet of the heat recovery unit.

[0064] In FIG. 3, the heater (220) and the heat recovery unit (310) are shown separately for ease of understanding, but the heater (220) may be configured to be included in the heat recovery unit (310). Of course, the heater (220) and the heat recovery unit (310) may also be configured separately.

[0065] Referring further to FIG. 3, the exhaust gas passes through an economizer (123) and a denitrifier (131) to remove nitrogen oxides. At this time, the exhaust gas temperature is expected to be approximately 300°C to 400°C, and after passing through a Gas Air Heater (GAH) (132), it becomes 175°C to 170°C, moves to an electrostatic precipitator (136), and is discharged through a blower (150) → flue gas desulfurization unit (160) to a chimney (170).

[0066] The combustion gas extracted from the thermal power plant must be recovered to the front end of the electrostatic precipitator (136) or similar device if it needs to undergo dust collection and desulfurization depending on the composition of the fuel. At this time, since the flow rate of the combined combustion gas is high, it is returned to the combustion gas line so that it can be controlled to a value lower than the environmental regulation value depending on the ratio with the flow rate passing through the environmental facility (i.e., the front end of 136, the front end of 150, the front end of 160, the front end of 170, etc. in FIG. 4 are possible), or if it is a clean fuel, it is vented directly to the outside.

[0067] In addition, depending on the dust content, it can be recirculated and diluted or discharged immediately. If the exhaust gas contains environmental pollutants exceeding the regulatory limit, the exhaust gas line of the thermal power plant is selected to be sent to an appropriate location, such as the upstream side of the electrostatic precipitator (136) or the upstream side of the flue gas desulfurization unit (160), taking into account environmental regulatory limits or pressure and temperature balance.

[0068] In addition, if the exhaust gas of a thermal power plant is used only as a gas air heater (GAH) (132) as in the conventional way, only heat up to about 175°C can be utilized, but if the exhaust gas is extracted and used in a heat recovery power generation system, the temperature up to 90-95°C can be utilized and additional power output can be obtained, so the power generation efficiency can be increased and the power can be converted into an eco-friendly power plant.

[0069] In addition, the cooler (not shown) of the thermal power plant and the cooler (240) of the array power generation block (140) can be connected.

[0070] The condenser (cooler) of a thermal power plant is used to cool water (steam), and since a cooler is also required in the heat generation block, the condenser (cooler) of the thermal power plant can be used simultaneously to cool the working fluid of the heat generation block.

[0071] FIG. 4 is a gas temperature curve of a 500MW class power generation boiler according to an embodiment of the present invention. Referring to FIG. 4, the capacity of Korean standard coal power plants is approximately 500MW, and many are installed and operating domestically. Recently, due to environmental pollution issues such as fine dust generated from coal power generation, there are facilities subject to retrofitting, making them suitable for integration.

[0072] The outlet gas temperature of the furnace is approximately 1100°C. The outlet temperature of the economizer (123) (i.e., the inlet of the air preheater (132)) is approximately 370°C. The optimal connection location in terms of temperature is the outlet of the economizer (123). Since the combustion gas flow rate required by the heater (220) of the heat recovery heat generation block (140) is less than the combustion gas flow rate generated in the boiler of the thermal power plant, some of the gas flow can be bypassed and used.

[0073] If possible, it is preferable to install it at the rear end of the denitrification unit (131) so that the NOx pollution regulation limit is satisfied without installing a separate denitrification unit (131). However, if it is difficult to satisfy environmental pollution regulation limits such as SOx and dust, the outlet of the heater (220) of the heat generation block (140) can be installed at the inlet of the electrostatic precipitator (136) of the thermal power plant to satisfy the regulation limits for dust and SOx. In addition, the insufficient air pressure loss can be compensated for by installing a separate suction fan to balance the overall pressure.

[0074] Referring to FIG. 4, curves (410, 420, 430) between the heat transfer surface position and the gas temperature are shown. Specifically, the Boiler Maximum Continuous Rating curve (410), 100% output curve (420), and 75% output curve (430) are shown. In other words, it shows the general temperature range of the combustion gas according to the position of the heat transfer surface of the thermal power plant.

[0075] FIG. 5 is a gas temperature curve of a 100MW class power generation boiler according to an embodiment of the present invention. The 100MW class power generation facility is the lowest capacity power generation facility supplied in Korea as a purely power generation boiler, and it is a facility that was introduced during the initial construction phase in Korea and is currently in operation.

[0076] Currently, the equipment is subject to disposal or repowering in terms of environmental pollution and equipment lifespan, so it is possible to connect the heat recovery power generation block. The inlet gas temperature of the denitrifier (131) is 430°C or lower. The outlet gas temperature of the denitrifier (131) is approximately 320°C, making it suitable for heat recovery power generation. The insufficient heat can be compensated for by methods such as increasing the gas flow rate. Referring to FIG. 5, the Boiler Maximum Continuous Rating curve (510), 100% output curve (520), and 75% output curve (530) are shown.

[0077] Additionally, the methods described in connection with the embodiments disclosed herein may be implemented in the form of program instructions that can be executed through various computer means, such as a microprocessor, a processor, a CPU (Central Processing Unit), etc., and recorded on a computer-readable medium. The computer-readable medium may include program (instruction) code, data files, data structures, etc., either alone or in combination.

[0078] The program (instruction) code recorded on the above medium may be those specifically designed and configured for the present invention, or those known and available to those skilled in the art of computer software. Examples of computer-readable recording media may include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs, DVDs, and Blu-rays; and semiconductor memory devices specifically configured to store and execute program (instruction) code, such as ROMs, RAMs, and flash memory.

[0079] Here, examples of program (instruction) code include not only machine code, such as that generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter, etc. The aforementioned hardware device may be configured to operate as one or more software modules to perform the operation of the present invention, and vice versa. Explanation of the symbols

[0080] 100: Thermal power plant performance improvement system. 102: Boiler 103: Flue 110: High temperature part 111: Plate-type superheater 112: Final superheater 113: Final Reheater 120: Medium temperature 121: Cold reheater 122: Primary superheater 123: Economizer 130: Low temperature section 131: Denitrifier 132: Air preheater 136: Electrostatic precipitator 140: Array generator block 150: Ventilator 160: Flue gas desulfurizer 170: Chimney 210: Damper 220: Heater 230: Double heat exchanger 240: Cooler 250: Compressor 260: Turbine 270: Generator

Claims

Claim 1 A boiler (102) of a thermal power plant; a flue (103) connected to the boiler (102) and guiding exhaust gas generated from the boiler (102); and includes an array power generation block (140) connected to the above-mentioned year (103) and generating power using a portion of the heat from the exhaust gas; wherein the array power generation block (140) is connected to the downstream end of a denitrification unit (131) that is placed in the low-temperature section (130) of the boiler (102) and removes harmful substances from the exhaust gas; and the array power generation block (140) includes: a damper (210) for introducing the exhaust gas; a heater (220) for heating a working fluid using the introduced exhaust gas; a turbine (260) that rotates using the heated working fluid; a generator (270) connected to the turbine (260) and rotated by the turbine (260) to generate power; a compressor (250) that compresses the working fluid passing through the turbine (260) to produce a compressed working fluid; and a heat exchange is performed between the compressed working fluid discharged from the compressor (250) and the working fluid passing through the turbine (260). Double heat (230); A thermal power plant performance improvement system capable of changing the capacity of a fan, characterized in that it includes a cooler (240) that cools the working fluid heat-exchanged by the above-mentioned heat exchanger (230); wherein the above-mentioned heat exchanger block (140) includes a heat recovery unit (310) connected to the output end of the above-mentioned heater (220) to release the exhaust gas into the atmosphere or return it to the above-mentioned flue (103); wherein a fan (150) is installed to balance the pressure within the above-mentioned flue (103) and the capacity of the fan is changed, and the heat recovery unit (310) is connected to the front or rear end of a flue gas desulfurization unit (160) installed within the above-mentioned flue (103) and installed at the front end of the chimney (170) to return the exhaust gas to the front or rear end of the flue gas desulfurization unit (160), and the pressure within the above-mentioned flue (103) is maintained constant using an additional blower.

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